The present invention relates to an audio/control head provided in a video recorder apparatus such as a VCR (Video Cassette Recorder) or VTR (Video Tape Recorder) and a method of assembling cores of the audio/control head.
Conventionally, a magnetic head provided in a video recorder apparatus such as a VCR employs an audio/control head (referred to as an A/C head hereinafter) which comprises two cores mounted in a sealed case, an audio core for recording and playing back audio signals and a control core for recording and playing back control signals. It is essential in such a video recorder apparatus that the two cores are precisely mounted on a core holder with a pitch length therebetween (referred to as a core pitch) held constant along a direction perpendicular to the tape transfer direction for accurately playing back the audio signals and control signals recorded by another video recorder apparatus.
FIGS. 8 and 9 illustrate a conventional method of mounting the two cores on the core holder in an A/C head. As shown in FIGS. 8 and 9, the conventional method of mounting the two cores comprises the steps of pressing the two, audio and control, cores 2, 3 and a jig 100, which is sandwiched between the two cores for determining a core pitch P1, together inwardly from the outside using another jig 102, applying an adhesive material 101 to between the two cores 2, 3 and the core holder 11, and dried out together with the jigs in a drying furnace. This allows the two cores 2 and 3 to remain spaced by the core pitch P1 as having been mounted. It is also necessary for mounting the two cores 2 and 3 to have the core projecting distance P2 held at a constant value as shown in FIG. 8. For the purpose, the two cores 2 and 3 are mounted with the core projecting distance P2 held constant using a further positioning jig.
A modified method of mounting magnetic cores in such an apparatus is disclosed in Japanese Utility-model Laid Open Publication (HEI)2-89604, where as the magnetic cores are positioned in a set of molds, a core holder is cast so that the two cores are mounted to the core holder with the use of no adhesive.
Another modified method is disclosed in Japanese Utility-model Laid Open Publication (HEI)5-21682, where a pair of members which incorporate two magnetic cores respectively in an A/C head are sandwiched between specifically configured set springs to inhibit positional discrepancy between the paired members. Moreover, a further modified method is disclosed in Japanese Utility-model Laid Open Publication (SHO)58-144614 where a record/playback head in an A/C head has holes provided therein for ease of mounting an audio erase head thereto.
However, the conventional apparatus employing the jigs for determining the core pitch has some drawbacks that the jigs are too many to be dried at the drying step, that the jigs may hardly be uniform in the dimensions, and that the jigs may easily be declined in the dimensions when worn out or applied with adhesive, hence failing to maintain the core pitch constant. Any arrangement disclosed in Japanese Utility-model Laid Open Publication (HEI)2-89604, (HEI)5-21682, or (SHO)58-144614 is impossible to reduce the number of the jigs for determining the core pitch.
The present invention has been developed for eliminating the foregoing drawbacks and its object is to provide an audio/control head which can determine the core pitch without using any jig in the assembly of cores, thus reducing the number of jigs required. Also, the core pitch can be increased in the accuracy, hence ensuring the stable characteristics of the head.
As a feature of the present invention for achievement of the object, an audio/control head is provided comprising an audio core for recording and playing back audio signals, a control core for recording and playing back control signals, and a core holder for holding the cores, the audio core and the control cores spaced from each other by a predetermined pitch length along a direction perpendicular to the direction of tape transfer and having distal end surfaces thereof arranged to be a tape contact surfaces so that the audio signals and the control signals can be recorded and played back on a tape, wherein the core holder includes, positioning portions for determining the pitch length between the two cores along the direction perpendicular to the direction of tape transfer and, pressing portions having an elasticity for pressing inwardly the cores against the positioning portions from the outer side of the perpendicular direction.
As the core members are held directly on the positioning portions of the core holder, they are pressed against the positioning portions by the pressing tabs in the above arrangement. Accordingly, the pitch length or core pitch between the two cores can be determined along the direction perpendicular to the direction of tape transfer, with no use of a specific jig. The number of jigs required for assembling the cores will be reduced. Also, the effect of variations or faults in the dimensions of the jigs will be minimized thus enhancing the accuracy of the core pitch.
It may be desired that while the core holder is formed by molding a resin material or by punching a pattern, its positioning portions are at least two spaced from each other along the depthwise direction inwardly of the distal ends of the cores and its pressing portions are located between the two positioning portions along the depthwise direction of the cores. While the cores are positioned and held with the at least two positioning portions and the pressing portions of the core colder, they are pressed by the pressing portions between the two positioning portions along their depthwise direction. This can inhibit the cores from tilting or dislocating.
According to a feature of the present invention, a method of assembling cores of an audio/control head which comprises an audio core for recording and playing back audio signals, a control core for recording and playing back control signals, and a core holder for holding the cores, the audio core and the control cores spaced from each other by a predetermined pitch length along a direction perpendicular to the direction of tape transfer and having distal end surfaces thereof arranged to be a tape contact surfaces so that the audio signals and the control signals can be recorded and played back on a tape, is provided comprising the steps of: preparing the core holder which includes positioning portions for determining the pitch length between the two cores along the direction perpendicular to the direction of tape transfer and pressing portions having an elasticity for pressing inwardly the cores against the positioning portions from the outer side of the perpendicular direction; holding the cores on the core holder; and drying together the cores and the core holder between which films of adhesive are applied.
In the method, the cores are securely held with the positioning portions and the pressing portions of the core holder so that its position can be determined along the direction perpendicular to the direction of tape transfer. The adhesive applied between the cores and the core holders held in the position is then dried. Accordingly, the cores can be mounted to the core holder without using any specific jig. As a result, the same effect as of the apparatus will be achieved.